Xu Luyan, Xie Huanjian, Chen Kuan, Feng Ruizhi, Zheng Donghui, Shou Haoge
School of Intelligent Manufacturing, Huanghuai University, Zhumadian 463000, China.
School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China.
Materials (Basel). 2025 Jul 14;18(14):3303. doi: 10.3390/ma18143303.
This work systematically investigates the Zn-content-dependent phase evolution (1-12 at.%) and its correlation with mechanical properties in as-cast Mg-2Y-Zn alloys. A sequential phase transformation is observed with the Zn content increasing: the microstructure evolves from X-phase dominance (1-2 at.% Zn) through W-phase formation (3-6 at.% Zn) to I-phase emergence (12 at.% Zn). Optimal mechanical performance is attained in the 2 at.% Zn-containing alloy, with measured tensile properties reaching 239 MPa UTS and 130 MPa YS, while maintaining an elongation of 12.62% prior to its gradual decline at higher Zn concentrations. Crystallographic analysis shows that the most significant strengthening effect of the X-phase originates from its coherent orientation relationship with the α-Mg matrix and the development of deformation-induced kink bands. Meanwhile, fine W-phase particles embedded within the X-phase further enhance alloy performance by suppressing X-phase deformation, revealing pronounced synergistic strengthening between the two phases. Notably, although both the I-phase and W-phase act as crack initiation sites during deformation, their coexistence triggers a competitive fracture mechanism: the I-phase preferentially fractures to preserve the structural integrity of the W-phase, effectively mitigating crack propagation. These dynamic interactions of second phases during plastic deformation-synergistic strengthening and competitive fracture-provide a novel strategy and insights for designing high-performance Mg-RE-Zn alloys.
本工作系统地研究了铸态Mg-2Y-Zn合金中锌含量依赖的相演变（1-12原子百分比）及其与力学性能的相关性。随着锌含量的增加，观察到连续的相变：微观结构从以X相为主（锌含量为1-2原子百分比），经过W相形成（锌含量为3-6原子百分比），到I相出现（锌含量为12原子百分比）。含2原子百分比锌的合金获得了最佳力学性能，测得的拉伸性能为抗拉强度239MPa和屈服强度130MPa，同时在锌浓度较高时逐渐下降之前保持12.62%的伸长率。晶体学分析表明，X相最显著的强化效果源于其与α-Mg基体的共格取向关系以及变形诱导扭折带的形成。同时，嵌入X相中的细小W相颗粒通过抑制X相变形进一步提高合金性能，揭示了两相之间明显的协同强化作用。值得注意的是，尽管I相和W相在变形过程中都作为裂纹萌生位点，但它们的共存引发了一种竞争断裂机制：I相优先断裂以保持W相的结构完整性，有效减轻裂纹扩展。第二相在塑性变形过程中的这些动态相互作用——协同强化和竞争断裂——为设计高性能Mg-RE-Zn合金提供了一种新策略和见解。
